The present invention relates to a device for repairing, by the use of a chemical repair liquid, cracked shatterproof glass such as windshields on an automobile.
An autommobile windshield is made of shatterproof glass in that the glass contains three laminates: an outer glass lamination, an internal synthetic resin lamination which imparts the shatterproof characteristics, and an inner glass lamination. Although an automobile windshield is shatterproof, it readily forms conical cracks when it is hit by a rapidly moving small pebble or other object. Usually, these conical cracks are formed when a cone-shaped piece of glass is separated, or partially separated from the external glass lamination, creating an air cavity under the surface of this outer glass lamination. If un-repaired, the air in this cavity eventually expands, causing a separation or a cracking of the glass to make room for its expansion. The result is the requirement of replacing the whole windshield, a very expensive requirement.
The repair of conical cracks on windshields usually is accomplished by injecting a polymeric repair liquid into the air cavity of the damaged area. The repair liquid dries and hardens, either by itself or induced by other means. The surface of the glass at the repair site is then either leveled or leveled and polished. The conical cracks are, in effect, cured. The repair of an automobile windshield is definitely less expensive that the replacement of the whole windshield.
Windshield repair devices and repair methods have been patented in the U.S. The general principle is to inject a repair liquid into conical cracks by means of a device that can be positioned around the cracks on the windshield. The device is usually held in place by a partial vacuum environment. The partial vacuum environment also serves to evacuate the cracks so that the repair liquid can completely fill the cracks.
U.S. Pat. No. 4,047,863, issued to McCluskey et al., discloses an apparatus for repair of shatterproof glass by the introduction of a repair liquid into the damaged area. A vacuum is applied to an enclosure surrounding the damagd area. The vacuum is intermittently released, by introducing air into the evacuated area, and reapplied to the area. The vacuum not only holds the apparatus in place but also helps to fill the crack with the repair liquid.
Klettke U.S. Pat. No. 4,385,015 teaches a windshield repair device. The device comprises a vacuum cup with a built-in piston and cylinder assembly. The cylinder assembly has a transverse opening so that when the piston is partly withdrawn, gas bubbles can be drawn out of the repair liquid by the vacuum holding the cup in place against the glass. Afterward, the piston closes off repair liquid communication through the transverse opening in the cylinder and the piston is used to force the repair liquid into the damaged area. Thus the cylinder not only serves as a reservoir for repair liquid but also allows the vacuum environment in the cup to remove gas bubbles from the repair liquid.
U.S. Pat. No. 3,765,975 to Hollingsworth teaches a method of repairing a pockmarked safety glass windshield. The patent describes a cup-shaped body held tightly over the pockmark area and fitted with a movable pointed probe and a removable syringe. The body of the device is held in place by a supporting frame attached to the windshield by rubber suction cups. Again, the vacuum environment that held the body in place is in direct communication with the pockmark area.
Luhman U. S. Pat. No. 3,988,400 describes a method of repairing cracked windshields. The apparatus disclosed includes a frame supported by two pairs of suction cups which can be pressed against the outer face of the windshield to keep the frame in a fixed position straddling the crack spot. A flexible dam forms a reservoir for the repair liquid. A probe over the flexible dam is used to squeeze the repair liquid into the crack.
Miller U. S. Pat. No. 4,032,272 teaches a windshield repair device. The device evacuates the atmosphere in the first enclosure around the pockmark and also seals off the immediate area surrounding the pockmark. This first enclosure has two outlets connected to the exterior of the device. A second outer enclosure can be evacuated to hold the device in place. Air, however, can be introduced into this second enclosure by opening a vacuum connection. The repair liquid is forced under pressure into the damaged area in the first enclosure.
U.S. Pat. No. 3,993,520 to Werner et al. discloses a windshield repair apparatus and method. The device has an injector tub which is held by a bridge member. The bridge member is situated in a spaced relationship to the windshield and adjacent to the crack. The piston of the injector tub can be reversed to create a partial vacuum condition and is also used to force the repair liquid into the crack.